Device and method for inspecting material

ABSTRACT

Material is inspected using a device that includes a sensor and an illumination unit. A test light is emitted by the illumination unit and is received by the sensor unit after reflecting off or shining through the material. This received light is evaluated in an evaluation unit. The illumination unit is provided with at least two light sources that emit test lights each having a different color. The sensor unit is provided with at least two color channels that are adapted to the different test lights of the light source.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is the U.S. national phase, under 35 USC 371, ofPCT/DE2003/002466, filed Jul. 22, 2003; published as WO 2004/017266 A1on Feb. 26, 2004 and claiming priority to DE 102 34 084.6, filed Jul.26, 2002, the disclosures of which are expressly incorporated herein byreference.

FIELD OF THE INVENTION

The present invention is directed to an arrangement and to a method forinspecting material. A sensor device received light from an illuminationdevice that includes several light sources that emit inspection light.

BACKGROUND OF THE INVENTION

Material inspecting arrangements are used, although not exclusively, forinspecting printed sheets which have been imprinted with, for example,securities. In this connection, the sheet-shaped material is illuminatedby the use of an inspection light emanating from an illuminating device,and wherein the inspection light is either reflected at the surface ofthe material, in so-called incident light inspections, or shines throughthe material, in so-called transmitted light inspections. The inspectionlight is subsequently recorded by a sensor device, such as, for example,a camera, and the input signals detected in the course of thisinspection are evaluated in an evaluating unit.

An arrangement for use in inspecting sheet-shaped material is known fromWO 01/85586 A1. Two illuminating devices and two sensor devices areprovided in this prior arrangement, which devices are respectivelyassigned to each other. The first illuminating device is arranged, withrespect to its assigned sensor device, in such a way that the inspectionlight falls through the sheet-shaped material, so that a transmittedlight inspection is made possible. The second illuminating device isarranged, with respect to its assigned sensor device, in such a way thatthe inspection light from the second illuminating device is reflected bythe material, so that an incident light inspection is made possible. Asa result, it is therefore possible to perform both an incident lightinspection and a transmitted light inspection of the material to beinspected.

DE 44 34 168 A1, EP 0 952 438 A2, JP 10-185 690 A and U.S. Pat. No.3,120,782 all disclose arrangements for use in inspecting material bythe provision of a sensor device and of several light sources. The lightsources each respectively emit an inspection light of a different colorof the light.

GB 2 002 923 A and DE 15 12 179 B1 both show arrangements of lightsources for the provision of incident light and of transmitted light.

SUMMARY OF THE INVENTION

The object of the present invention is directed to on providing anarrangement and a method for inspecting material.

In accordance with the present invention, the object is attained by theprovision of an arrangement for inspecting materials that includes asensor device and an illumination device. Inspection light is emittedfrom the illumination device from several lights sources, is received bythe sensor device, and is evaluated in an evaluation device. Theillumination device has at least two light sources that each emits aninspection light which is colored differently from the light from otherones of the illumination device. The sensor has at least two colorchannels that are matched to the different inspection lights. Bothincident light inspections and transmitted light inspections can beaccomplished separately, yet at the same time.

A particular advantage of the present invention lies in that only onesensor device, such as, for example a color camera, a color line cameraor a CCD camera, is required for being able to check various testingcriteria by use of the subject arrangement. In this case, the presentinvention rests on the basic idea that the different testing criteriaare checked by the use of light of different colors. Therefore, theillumination device has at least two light sources, each of which emitsan inspection light of a different light color, i.e. of a different wavelength. At least two different color channels are provided in the sensordevice. It is possible by the provision of this arrangement to recordlights of different colors using the sensor device, which differentcolored lights can then be separately evaluated in the evaluation unit.The input signals recorded by the sensor device can each be processedseparately from each other in accordance with the respective color oflight by use of the different color channels in the sensor device sothat, while using only one sensor device, the different testing criteriaare not mixed up.

It is particularly advantageous, in accordance with the presentinvention, if the light sources each emit an inspection light of asubstantially monochrome light color. These monochrome light colors canbe assigned, in a simple way, to the different color channels of thesensor device. The result is that an unintentional distortion orinfluencing of the input signals, in the different color channels, isessentially prevented.

The spectral position and/or the band width of the inspection lightemitted by the light sources is matched to the transmission curve of thesensor device.

Commercially available color cameras, which can be used as sensordevices in the arrangement in accordance with the present invention,customarily have three separate color channels for the colors red, blueand green. It is therefore particularly advantageous for theilluminating device to have three light sources, whose inspection lightsare matched to the respective properties of the three color channels.Three light sources, with the three monochrome light colors red, blueand green, for example, can be used for this purpose.

The arrangement of the present invention offers particular advantages ifthe light sources are arranged in different positions relative to thematerial that is to be inspected. As a result, it is possible to checkdifferent testing criteria by this arrangement of the lights sources indifferent positions, which correspond to the respective desiredpositions, while only a single sensor device must be provided.

In order to be able to adapt the arrangement of the present invention todifferent inspection purposes, it is particularly advantageous if thelight sources are displaceably supported or seated. This means that, bydisplacing the light sources, it then becomes possible to adapt thedifferent light sources to different testing criteria.

In accordance with a preferred embodiment of the present invention, onelight source has been arranged in such a way that the inspection lightshines through the material to be inspected. Moreover, a second lightsource has been arranged in such a way that the respective inspectionlight from this second light source is reflected by the material to beinspected. As a result, it is possible to achieve, that by thisarrangement, an incident light inspection, in which the inspection lightis reflected by the material, can be performed simultaneously with atransmitted light inspection, in which the inspection light falls orpasses through the material.

Only one sensor device is required for this combined incident light andtransmitted light inspection. The incident light inspection is processedin a first color channel, while the transmitted light inspection isprocessed in a second color channel.

Alternatively, or in addition to this first preferred embodiment, it isalso possible to arrange two light sources in such a way that thedifferent colored inspection lights are both reflected, at differentangles, by the material that is being inspected. With this secondpreferred embodiment, the input signals formed by the inspection lightin the sensor device are processed in different color channels, so thatdifferent testing criteria can be recorded and processed with the use ofonly a single sensor device.

BRIEF DESCRIPTION OF THE DRAWING

A preferred embodiment of the present invention is represented in thesole drawing FIGURE and will be described in greater detail in whatfollows.

The sole drawing FIGURE shows, in a schematic cross section, anarrangement for testing sheet-shaped material in accordance with thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The device for inspecting material, indicated generally at 01, in thesole drawing FIGURE includes a sensor device 02, which is embodied as acolor line camera, three light sources 03, 04, 06, which together forman illumination device, and a support 07.

The material 08 to be inspected, which material may be, in particular, asheet- or a web-shaped material 08, is introduced into the arrangement01 by the use of suitable conveying arrangements, which are notspecifically represented, and then lies flat on a top surface of thesupport 07. A recess or an aperture 09 is provided in the support 07, sothat inspection light 12 emitted by a light source 06, which is arrangedunderneath the support 07, can fall into or be received in a lens of thesensor device 02. The first light source 03 emits inspection light 10 ofthe first monochrome light color red. The second light source 04 emitsan inspection light 10 of the second monochrome light color blue. Thethird light source 6 emits the inspection light 12 of the thirdmonochrome light color green. The sensor device 02 has three separatelight channels for the light colors red, blue and green.

The process of the inspection of the image information, in particularthe print image, of the material 08 is performed as follows. After thematerial 08 has been arranged above the recess or aperture 09, the threelight sources 03, 04 and 06 simultaneously each emit their respectiveinspection light 10, 11 and 12 in the different light colors. The first,red inspection light 10 and the second, blue inspection light 11 arereflected at different angles at the surface of the sheet-shapedmaterial 08 and together fall into or are received in the lens of thesensor device 02. As a result, it is thus possible to perform anangle-dependent incident light inspection of the sheet-shaped material08. Simultaneously, the third, green inspection light 12 emitted by thethird light source 06 falls or passes through the sheet-shaped material08 and also into the lens of the sensor device 02. In this way, it ispossible, simultaneously with the two incident light inspectionsaccomplished by the first and second light colors red and blue, toperform a separate transmitted light inspection by use of the thirdlight color green. The assignment of the three different light colors tothe two different incident light and to the transmitted lightinspections is basically arbitrary and can be interchanged.

The first, second and third inspection lights 10, 11 and 12corresponding to the first, second and third different light colors red,blue and green, respectively, are processed in the sensor device 02 inseparate color channels and are passed on to an evaluating device, whichis not specifically represented. The image contents of each of theindividual color channels can be processed separately from each other inthe evaluation unit. However, it is, of course, also possible inaccordance with the present invention to bring the input signalsreceived on the separate color channels into correlation with each otherin order to be able, for example, to draw spatial conclusions.

While a preferred embodiment of a device and method for inspectingmaterial, in accordance with the present invention, has been set forthfully and completely hereinabove, it will be apparent to one of skill inthe art that various changes in the specific image to be inspected, thespecific structure of the support and the like could be made withoutdeparting from the true spirit and scope of the present invention whichis to be limited only by the following claims.

1-13. (canceled)
 14. A device for inspecting material comprising: asensor device; an illumination device; at least first and second lightsources in said illumination device; a first inspection light of a firstcolor emitted by said first light source, and a second inspection lightof a second color emitted by said second light source, said first andsecond colors being different; at least first and second color channelsin said sensor device, each of said at least first and second colorchannels being matched to said first and second inspection lightsemitted from said first and second light sources, said at least firstand second color channels receiving said first and second inspectionlights that are at least one of passed through and reflected by thematerial; and an evaluation device adapted to process image content ofeach of said at least first and second color channels.
 15. The device ofclaim 14 wherein said at least first and second inspection lightsemitted by said at least first and second light sources of saidillumination device, after one of passing through and being reflected bythe material, are recorded together by said sensor device and separatelyevaluated in said evaluation device.
 16. The device of claim 14 whereineach of said at least first and second inspection lights are each asubstantially monochrome light color.
 17. The device of claim 14 whereinat least one of said spectral position and bandwidth of each saidinspection light is matched to a transmission curve of said sensordevice.
 18. The device of claim 14 wherein said sensor device is a colorline camera.
 19. The device of claim 14 wherein said sensor device is aCCD camera.
 20. The device of claim 14 wherein said sensor device hasfirst, second and third color channels, wherein said illumination devicehas first, second and third light sources and wherein each first, secondand third light sources emit first, second and third inspection lightsmatched to properties of said first, second and third color channels.21. The device of claim 14 wherein said at least first and second lightsource are arranged at first and second different positions relative tothe material.
 22. The device of claim 21 wherein said at least first andsecond light sources are each displaceable.
 23. The device of claim 14wherein at least one of said at least first and second inspection lightspasses through the material and another of said at least first andsecond inspection lights is reflected by the material.
 24. The device ofclaim 14 wherein at least one of said at least first and secondinspection lights is reflected by the material at a first angle and atleast a second of said at least first and second inspection lights isreflected by the material at a second angle.
 25. A method for inspectingmaterial including: providing a sensor device; providing an illuminationdevice; providing at least first, second and third light sources in saidillumination device; directing first, second and third inspection lightsfrom said first, second and third light sources, said first, second andthird inspection lights having first, second and third differentlycolored lights; providing at least first, second and third colorchannels in said sensor device and being matched to said first, second,and third inspection lights; providing an evaluation unit for separatelyevaluating said first, second and third color channels; reflecting afirst one of said inspection lights, at a surface of the material, fromsaid first light source to said first color channel of said sensordevice; reflecting a second one of said inspection lights, at a surfaceof the material, from said second light source to said second colorchannel of said sensor device; passing a third one of said inspectionlights through the material from said third light source to said thirdcolor channel of said sensor device; and using said first and saidsecond reflected inspection lights and said third passed throughinspection light for simultaneously and separately performing twoincident light inspections and one transmitted light inspection on saidmaterial.
 26. The device of claim 14 wherein the material is a printedproduct including image information.
 27. The method of claim 25 furtherincluding providing the material as a printed product including imageinformation.